A hybrid imaging array and method for using the same is disclosed. The image array includes a low-light imaging array and a color imaging array. The two imaging arrays can be utilized separately or in conjunction with one another. The low-light imaging array is optimized for night vision or situations in which the light levels are too low to allow a conventional color image to be formed by the color imaging array. The color imaging array is optimized for daylight or color photography. The low-light imaging array can be utilized in conjunction with the color imaging array to provide a color image with reduced noise.
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1. An imaging array comprising: a low-light imaging array comprising: a plurality of rows and columns of low-light pixels; and a low-light processor comprising a plurality of low-light bit lines, each low-light pixel in each column of low-light pixels being connected to one of said low-light bit lines corresponding to that column of low-light pixels; and a color imaging array comprising: a plurality of rows and columns of color pixels; and a color processor comprising a plurality of color bit lines, each color pixel in each column of color pixels being connected to one of said color bit lines corresponding to that column of color pixels, wherein each low-light pixel comprises a photodiode that is characterized by a first area and wherein each color pixel comprises a photodiode that is characterized by a second area, said second area being less than said first area, and wherein said color processor comprises a variable gain amplifier coupled to one of said color bit lines, said variable gain amplifier having a gain that is set in response to an estimate of charge stored in a pixel currently connected to that bit line.
The imaging device combines a low-light sensor and a color sensor on the same chip. The low-light sensor has pixels with larger photodiodes, making them more sensitive to light. Each column of low-light pixels connects to a low-light processor via bit lines. The color sensor has pixels with smaller photodiodes. Each column of color pixels connects to a color processor using color bit lines. The color processor includes a variable gain amplifier for each column of pixels. The gain of the amplifier adjusts based on the estimated light level detected by the color pixel, improving image quality by compensating for low light conditions.
2. The imaging array of claim 1 wherein there is one row of color pixels corresponding to each row of low-light pixels, and wherein said pixels on each row of low-light pixels and said corresponding row of color pixels are connected to a row bus that includes a row select line that causes each low-light pixel in that row to be connected to a corresponding one of said low-light bit lines and each color pixel in said corresponding color pixel row to be connected to a corresponding one of said color bit lines.
The imaging array consists of rows of alternating low-light pixels and color pixels. Each row of low-light pixels has a corresponding row of color pixels. Each row of pixels connects to a shared row bus that includes a row select line. When the row select line is activated, each low-light pixel in that row connects to its corresponding low-light bit line in the low-light processor, and each color pixel in the corresponding color row connects to its color bit line in the color processor. In other words, for every row of low-light pixels, there's a matching row of color pixels, simplifying row-by-row readout.
3. The imaging array of claim 1 wherein said estimate of charge is obtained from a light measurement in a corresponding low-light pixel.
In the imaging array that combines low-light and color sensors, the gain of the variable gain amplifier in the color processor is controlled by an estimate of the light intensity. This estimate is derived from the light measurement from a corresponding low-light pixel. Essentially, the reading from a nearby, more sensitive, low-light pixel is used to automatically adjust the amplification applied to the signal from the color pixel, improving the color image in low light.
4. The imaging array of claim 1 wherein at least one of said color pixels comprises a color filter that blocks light outside a predetermined portion of the optical spectrum from reaching said photodiode in that pixel.
The imaging array combines a low-light sensor and a color sensor. At least some of the color pixels contain color filters. These filters block certain wavelengths of light, allowing only a specific part of the color spectrum to reach the photodiode in that pixel. This filtering is crucial for generating color images by separating the incoming light into its red, green, and blue components, as is typical in a Bayer filter configuration.
5. The imaging array of claim 4 wherein said low-light pixels do not include a filter that blocks light within a frequency band from 400 nm to 1100 nm from entering said photodiodes in those pixels.
This imaging array contains low-light pixels and color pixels where the color pixels have color filters. Crucially, the low-light pixels do *not* have filters blocking light in the visible and near-infrared spectrum (400nm to 1100nm). This unfiltered approach allows the low-light pixels to capture as much light as possible, including infrared, enhancing their sensitivity for night vision applications, while the color pixels capture only the visible light needed for color imaging.
6. The imaging array of claim 4 wherein said color filter comprises an infrared filter that blocks light with wavelengths greater than 700 nm from reaching said photodiode in said color pixel.
The imaging array contains low-light pixels and color pixels where the color pixels have color filters. In this version, the color filter is specifically an infrared (IR) filter. This filter blocks light with wavelengths greater than 700 nm from reaching the photodiode in the color pixel. This is useful for generating clean color images by preventing infrared light from contaminating the color data, while still allowing the low-light pixels to capture IR light.
7. An imaging array comprising: a low-light imaging array comprising: a plurality of rows and columns of low-light pixels; and a low-light processor comprising a plurality of low-light bit lines, each low-light pixel in each column of low-light pixels being connected to one of said low-light bit lines corresponding to that column of low-light pixels; and a color imaging array comprising: a plurality of rows and columns of color pixels; and a color processor comprising a plurality of color bit lines, each color pixel in each column of color pixels being connected to one of said color bit lines corresponding to that column of color pixels, wherein each low-light pixel comprises a photodiode that is characterized by a first area and wherein each color pixel comprises a photodiode that is characterized by a second area, said second area being less than said first area, wherein at least one said color pixels comprises a color filter that blocks light outside a predetermined portion of the optical spectrum from reaching said photodiode in that pixel, wherein said color filter comprises an infrared filter that blocks light with wavelengths greater than 700 nm from reaching said photodiode in said color pixel, wherein said infrared filter comprises a layer of metal having holes therein, said layer of material overlying said photodiode in said color pixel.
This imaging device combines a low-light sensor and a color sensor on the same chip. The low-light sensor has pixels with larger photodiodes. Each column of low-light pixels connects to a low-light processor. The color sensor has pixels with smaller photodiodes. Each column of color pixels connects to a color processor. At least some of the color pixels contain color filters. These color filters are infrared (IR) filters, blocking light with wavelengths greater than 700 nm. The IR filter is a layer of metal with tiny holes that sits above the photodiode in the color pixel, blocking unwanted wavelengths of light.
8. The imaging array of claim 7 wherein said layer of metal comprises a layer of copper, silver, or gold.
This imaging array has low-light and color sensors with a metal-layer infrared (IR) filter in the color pixels. The metal used for this IR filter can be copper, silver, or gold. The perforated metal layer reflects infrared light but allows visible light to pass through the holes, achieving the desired filtering effect for each color pixel.
9. The imaging array of claim 7 wherein said imaging array is constructed in a CMOS fabrication process and wherein said metal layer is one of a plurality of layers provided in that fabrication process for constructing electrical conductors for connecting components in said imaging array.
In this imaging array with low-light and color sensors, the metal layer used as an infrared filter is integrated into a CMOS fabrication process. This means the metal layer is one of several already present in the manufacturing process for building electrical connections between components in the array. The CMOS fabrication process essentially uses existing metal layers to create the IR filter, minimizing additional manufacturing steps and costs.
10. A method for forming an image of a scene, said method comprising forming an image of said scene on an imaging array comprising: a low-light imaging array comprising: a plurality of rows and columns of low -light pixels; and a low-light processor comprising a plurality of low-light bit lines, each low-light pixel in each column of low-light pixels being connected to one of said low-light bit lines corresponding to that column of low-light pixels; and a color imaging array comprising: a plurality of rows and columns of color pixels; and a color processor comprising a plurality of color bit lines, each color pixel in each column of color pixels being connected to one of said color bit lines corresponding to that column of color pixels, wherein each low-light pixel comprises a photodiode that is characterized by a first area and wherein each color pixel comprises a photodiode that is characterized by a second area, said second area being less than said first area; and reading out said low-light imaging array or said color imaging array, and wherein said estimated image is used to set an exposure time for each row in said color imaging array, at least two of said rows having different exposure times.
This invention relates to imaging systems designed to capture high-quality images in varying light conditions, particularly in low-light environments. The system combines a low-light imaging array with a color imaging array to optimize image capture. The low-light imaging array consists of multiple rows and columns of low-light pixels, each connected to a dedicated bit line in its column. Similarly, the color imaging array contains multiple rows and columns of color pixels, each connected to a corresponding color bit line. The photodiodes in the low-light pixels are larger than those in the color pixels, enhancing sensitivity in low-light conditions. The system reads out either the low-light or color imaging array, depending on the scene's lighting conditions. Additionally, the system uses an estimated image to set different exposure times for each row in the color imaging array, allowing at least two rows to have distinct exposure times. This adaptive exposure control improves dynamic range and image quality in scenes with varying brightness levels. The invention addresses the challenge of capturing detailed, color-accurate images in both bright and low-light environments by leveraging specialized pixel designs and adaptive exposure techniques.
11. The method of claim 10 comprising forming an estimated image with said low-light imaging array and using said estimated image to set parameters used in reading out said color imaging array.
The method involves using an imaging array that has both a low-light sensor and a color sensor. First, an estimated image is created using the low-light sensor. This estimated image is then used to determine the settings for reading out the color sensor. This allows the low-light sensor to act as a guide, enabling the color sensor to capture a better image by using the information from the low-light image to make smart adjustments during the color image capture.
12. The method of claim 11 wherein said color processor comprises a variable gain amplifier coupled to one of said color bit lines and wherein said estimated image is used to set a gain for said variable gain amplifier.
This image creation method uses an imaging array with low-light and color sensors. After creating an estimated image with the low-light sensor, this estimated image is used to set the gain for a variable gain amplifier within the color processor. The color processor has a variable gain amplifier for each column of color pixels. Essentially, the low-light image guides the amplification applied to the color pixel signals, enhancing the brightness and clarity of the color image in low-light areas.
13. The method of claim 11 wherein said color image comprises a plurality of pixel signal values and corresponding variable gain amplifier values.
This image creation method uses an imaging array with low-light and color sensors. The method involves capturing a color image that consists of pixel signal values from the color pixels as well as corresponding variable gain amplifier values. This means that for each color pixel, there's a signal strength value and a gain value indicating how much that signal was amplified, providing complete information for image processing algorithms.
14. The method of claim 10 further comprising blocking light having a wavelength greater than 700 nm from reaching said color pixels while allowing that light to reach said low--light pixels.
This image creation method uses a hybrid imaging array where light with a wavelength greater than 700 nm (infrared light) is blocked from reaching the color pixels but allowed to reach the low-light pixels. The color pixels have IR filters. The low-light pixels do not. This filtering strategy enables the color sensor to capture clean color data without IR contamination, while the low-light sensor can leverage the additional light from the infrared spectrum to enhance its sensitivity.
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September 28, 2010
March 7, 2017
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